The present invention relates to an electrical connector part provided for being coupled with a matching connector part by a front face, said connector part comprising                an insulating housing provided with a plurality of sockets for receiving a contact, which have a rear contact insertion end,        a joint, which is provided with a plurality of cable passages corresponding to the sockets and which is placed in said housing behind the sockets, and        a cable-guiding grid, which is fixed in the housing behind the joint, supporting the latter, said grid being provided with a plurality of cable passages corresponding to the sockets.        
Such an electrical connector part is described, for example, in the French patent application published under No. 2,830,132.
In a connector part of this type, referred to as a “partially populated” connector, some of the connection paths may be unused, so that, in order to ensure the sealing of the connector, it is necessary to block the corresponding passages of the joint (also referred to as a “grommet”). To do this, a blocking piece is inserted into each of the unoccupied sockets and afterwards allowed to remain in the connector part. The blocking piece is generally composed of a piece of molded plastic, the outer shape of which reproduces in part the shapes of a contact and of an end section of the cable that it replaces.
The insertion of such blocking pieces represents a relatively significant operating time on the assembly line. If the operation is performed manually, it requires a sustained attention on the part of the operator in order to block all of the unoccupied paths. If the operation is performed automatically, it requires a specific, relatively perfected and costly tooling.
In addition, this operation can be the origin of serious malfunctions of the connector if an unoccupied path is not blocked or is incorrectly blocked.
Also known in the prior art are joints of the grommet type in which is formed a thin membrane that blocks all of the socket passages at the level of a median section of the passages. This membrane is designed to be pierced in the passages receiving a contact as a result of the insertion of the contact itself, whereas the membrane stays intact in the unused passages.
Due to the position of the membrane in the interior of the joint, the state of the membrane is not apparent, so that it is difficult not only to prevent wiring mistakes, but also to detect them.
Such an arrangement additionally poses a substantial problem, which consists of reestablishing the sealing of the joint in the event that a contact is inserted by mistake in a path that is designed to be unused. In fact, if the mistake is discovered, the operator has to withdraw the contact and block the passage, for example, by using a plug, which constitutes an additional tedious operation.